The invention relates to the manufacture of a molded plastic top comprising an outlet opening connected by a tearable ring-shaped part to a cover serving as an impervious stopper prior to breaking. In the case of multi-dose packaging, this cover is used for the recapping of the opening. The top may be affixed to the open end of any container the opening of which is to be hermetically sealed prior to initial use and then be covered by a cap between uses.
The implementation of such tops avoids manufacturing caps separately and positioning these on the containers through costly industrial means. Any container for which the cost of manufacture constitutes an essential factor is particularly affected by this invention. It specifically involves producing flexible tubes intended to contain health products for mass consumption or even producing small-size containers, holding samples of cosmetic, health or parapharmacy products, often distributed free of charge.
The invention thus relates to two quite distinct fields in mass distribution, but for which packaging cost is an essential factor: the supplying of the general-consumption product at the lowest price and the supplying of samples, of cosmetic products for example, free of charge.
In the field of products for mass consumption, it has been sought for a long time to develop economical tops for flexible tubes intended, for example, to contain tooth paste. With the tube described in FR-A-2,712,258, the applicant has developed a top for a tube having a cover in the form of an easily-tearable inverted cap. The neck has a thick, ring-shaped inner rim which defines its opening and, on the other side of the tearable ring-shaped part, the part blocking the opening of the neck extends outward, forming a thick base which is joined to an outer cylindrical skirt.
Even if it resolves the economic problem initially posed, the tube according to FR 2,712,258 cannot be used completely under satisfactory conditions of convenience, cleanliness and hygiene. As a matter of fact, the product which was in contact with the surface of the cover is, immediately upon tearing of the ring-shaped part, on top of what has become a cap, which compels the user to begin by washing this cap if he does not wish to soil his hands. Moreover, this tube being intended for lower-cost distribution is not individually protected by an overwrap. Thus it is directly exposed to the open air in warehouses or on shelves and, in the course of this storage, the cover in the form of an inverted cap is likely to collect dust which adheres to the inner surface of the outer cylindrical skirt.
When the cover is used as a cap after tearing, this inner surface enters directly into contact with the outer surface of the neck, which itself has been exposed to dust throughout the storage period of the tube. There is a significant risk of tainting of the product which is close to the opening of the neck, which is prejudicial to the conditions of cleanliness customarily expected from the use of a tube, and in certain cases even may lead to non-conformity with health standards, since there is risk of product contamination.
In the second field of application, that of containers for samples, cosmetic-product samples currently are largely presented in the form of simple packets, difficult to tear and non-reusable. Unlike these simple packets, the contemplated sample is a true container, easy to uncap and reusable several times. In addition, it offers the advantage of having a form close to the packaging of the product actually marketed. Containers for samples certainly exist at the present time, but their embodiment does not differ from that of the commercial container: it requires separate manufacturing of the container and the cap, with a specific costly tamper-proofing device. The cost of manufacture of such containers for samples is justified only in the luxury trade. Now, it is sought here to propose containers for cosmetic-product samples for mass distribution, or even for small amounts of health or grooming products offered in the hotel trade.
Whether flexible tubes or containers for samples are involved, it thus is a question of producing them at a lower costs, whatever their form or material, but meeting the following criteria: preserving the cleanliness of the product contained at all times, in storage as well as in dispensing through the opening; having a tamper-proofing indicator and a cover reusable as a cap after tearing.
The applicant thus has sought to produce an economical top for a flexible tube or for any other container, easy to attach to the flexible tube or the container, comprising a neck always protected from dust, provided with a tamper-proofing indicator and topped with a cover which, after easy tearing, may be used as a cap sealing the tube hermetically and efficiently all throughout its use.
An initial purpose of the invention relates to a manufacturing process which results in the production of a top provided with at least a skirt, this either alone or attached to the main portion of a cap, being joined permanently by a ratchet mechanism on the top, near the cover.
This process comprises a step for manufacturing of the plastic top by any known molding technique (injection, compression, etc...), the top comprising an open end intended to be attached subsequently to the open end of the container or the flexible tube and comprising at its other end a neck the outlet opening of which is joined by a tearable ring-shaped part to a cover serving as an impervious stopper prior to breaking and then being used for recapping of the opening. The process also comprises a step for manufacturing of a plastic skirt by any known molding technique, the skirt being able to be alone or integral with a complete cap, and it is characterized in that:
said cover is extended beyond the outer surface of the neck by a plate the periphery of which is defined by a contour which has a common axis of symmetry with said tearable ring-shaped portion and is provided with at least three lugs;
said skirt is open at one end and its inner surface is at least partially cylindrical, its section following the exact shape of the periphery, except for the lugs, of the plate extending from the cover, the cylindrical portion of the inner surface being provided with at least three cavities intended to accommodate said lugs;
after formation of the top and the skirt, said skirt is guided along with respect to said plate, then drawn by its first end around same to the point of immobilization, this being brought about by the insertion of the lugs on the plate into the cavities on the inner surface of the skirt.
The top is molded with a lower central mold which defines its inner surface and a set of upper molds, central and peripheral, which define its outer surface. The top is composed of a shoulder and a neck. The shoulder has an open end intended to be attached by any known means to the open end of the container. If the latter is a flexible-tube body or any other container of a plastic compatible in fusion with the plastic of the top, fastening is achieved preferably by fusion: overmolding, mold compression, thermal welding, high-frequency or any other suitable welding method. If the container is another material, glass, metal or a plastic not compatible in fusion, fastening may be effected by gluing but, preferably, the shoulder is extended by joining means complementary to those of the container, such as screwing means or a ratchet mechanism.
The neck has any form whatever. It possesses, near the opening, a ring-shaped inner rim, delimited on its upper end by a tearable ring-shaped part which connects it to a cover topping the neck opening.
The plate, located in the extension of the cover, is molded in continuity of material with the latter. The plate and the cover extend appreciably perpendicularly to the axis of the opening. The peripheral contour of the plate, except for the lugs, embodies the outer contour of the upper section of the neck, located near the opening. It is in this sense that we have written: xe2x80x9cthe cover is extended beyond the outer surface of the neck.xe2x80x9d Thus, if the neck is not perfectly cylindrical, it is entirely possible that its base might be far more extended than its end bearing the opening, which may cause the periphery of said plate to be within an imaginary cylinder having its generatrix parallel to the axis of the neck and having the base of the neck for a directrix (see FIG. 8).
Moreover, the periphery of the plate is provided with at least three lugs which, when they are engaged in the cavities effected in the inner surface of the skirt, block any relative movement in rotation or translation, of said skirt with respect to the plate.
The skirt has an open end, intended to appear first at the time of drawing of the skirt around the plate. We shall call this end xe2x80x9cfirst endxe2x80x9d and the other end xe2x80x9csecond end.xe2x80x9d The inner surface of the skirt is at least partially cylindrical, with a generatrix parallel to the axis of the neck, the directrix following the exact shape of the periphery, except for the lugs, of the plate extending from the cover. The cylindrical portion of the inner surface is provided with at least three cavities intended to accommodate said lugs. The distance between these cavities and the first end is a function of the neck height to be protected. These cavities may or may not be traversal.
The skirt, once driven-in by its first end around the plate, encircles the outer surface of the neck. The form of the first end of the skirt is defined in terms of the height of the neck to be protected, so that the skirt comes close to the surface of the neck when driving-in is completed, yet without touching it. An improved efficacy for protection of the neck is obtained by selecting for the contour of the first end of the skirt, the contour of the neck section corresponding to the level to which the said first end of the skirt comes when driving-in is completed, expanded outward by a few tenths of a millimeter.
The second end of the skirt may be open or else connected in continuity of material at the base of a cap. The cap, in addition to its base and said skirt, also may be provided with one or several outer skirts, intended for its easy gripping and to enhance the esthetic appearance of the container as a whole.
The skirt has an outer surface of any shape whatsoever, compatible with the shapes imposed on the inner surface in the first end and the cylindrical portion, described above. It should be sufficiently thin and flexible with respect to the lugs so as not to deform the latter at the time of drawing of the skirt.
The lugs on the plate and the cavities in the skirt are complementary means of joining by locking in rotation and translation. When the skirt is driven-in around the plate to the point of immobilization, there is a joining in rotation and translation of the skirt and the cover+ plate unit. The cavities may be traversal; the apertures thus formed make it possible to accommodate lugs of considerable length, which improves the joining of the skirt and the top. Nonetheless, one may choose to keep these cavities closed at one end for reasons associated with the esthetic appearance of the periphery of the cap. In addition, lugs and cavities are presented here as complementary means of permanent joining: nothing prevents their respective positions from being reversed; that is, providing the skirt with lugs and the plate with cavities, or even providing the plate and skirt with any other complementary means of joining by locking in translation and rotation, such as combinations of complementary longitudinal channels and circumferential grooves/ribs.
Preferably, when the skirt is attached to the rest of a cap, the cylindrical portion of its inner surface extends as far as the second end and the cavities, provided on said cylindrical inner surface, are close to said second end. Thus, when the skirt has been driven-in around the plate to the point of trapping of the lugs in the apertures or cavities, the joining ensured by the lugs and the cavities is sufficiently rigid and close to the base of the cap to effectively transmit the force applied on the outer casing of the cap intended for tearing of the ring-shaped part.
When the skirt is implemented alone, with the second end open, the cavities may be implemented at a lesser or greater distance from the second end, nonetheless without being less than the thickness of the skirt. In this case, this skirt constitutes the skirt of the future cap, and the cover+ plate unit, once detached from the top, constitutes the base thereof. The joining ensured by the lugs and the cavities is rigid. The user applies a force directly to the skirt, preferably near the plate. This force is transmitted to the plate owing to the rigid lug-cavity joining; then, amplified by a xe2x80x9clever-armxe2x80x9d effect due to the geometry of the plate, it brings about the tearing of the ring-shaped part through a relative movement of the plate+ cover unit with respect to the neck.
So as to facilitate tearing, the ring-shaped inner rim of the neck and the cover+ plate unit are clearly thicker than the tearable ring-shaped part. Thus, they behave as shell elements resisting the forces, and the constraints are concentrated on the ring-shaped part.
The neck possesses, near the opening, a ring-shaped inner rim connected by the tearable ring-shaped part to a cover which tops the opening of the neck. The cover comprises a transition part between the plate-extension part and the tearable ring-shaped part. This transitional part is either a nipple if the diameter of the opening is small, for example in the case of containers for a sample; or a crown if the diameter is larger, for example in the case of tubes for toothpaste.
The nipple or crown has an axis of symmetry coinciding with the axis of the opening. After tearing of the ring-shaped part, the nipple or crown serves as a means for imperviousness.
The nipple or crown also may serve for recapping by repositioning in the opening and further driving-in with forcing, but this function may be ensured elsewhere, for example with complementary ratchet means located on the outer surface of the neck and on the inner surface of the skirt close to its first end.
In one form of the invention, tubes for samples are produced at lower cost by selecting preferably a specific form of nipple or crown making it possible, on the one hand, to combine the closing and imperviousness functions and, on the other, to ensure a tamper-proofing indicator function. This form already was described in FR2649676: the periphery of the crown or the nipple successively comprises, starting from the tearable ring-shaped part and going toward the connection at the base of the cover: an initial portion with the shape of a truncated cone, then a cylindrical portion with a diameter exceeding that of the opening, which we shall call an over-collar, a recessed shoulder, and finally a recessed cylindrical or truncated-cone-shaped portion.
The nipple or the crown is attached to the neck by the upper end of the ring-shaped inner rim defining the opening. The connection is delicate. It constitutes the tearable ring-shaped part, which may be described as an area of slight thickness extending on both sides of a frustum of a cone, as an extension of the first truncated-cone-shaped portion of the nipple or the crown and having a length ranging between 0.1 and 0.5 millimeters, separating the inner surface from the outer surface of the top.
After tearing, the neck thus has its opening defined by a micro-chamfer in the shape of a truncated cone, located at the upper end of the ring-shaped inner rim, resulting from breaking of the ring-shaped part. The inner ring-shaped rim has a height 5 to 10% less than the recessed cylindrical or truncated-cone-shaped part of the nipple or the crown, which itself has the shape of a truncated cone 1 and 3xc2x0 the small diameter of the recessed shoulder is on the other hand greater, typically from 3 to 6%, than the diameter of the opening, the diameter of the over-collar then exceeding the diameter of the opening by 6 to 10%, so as to ensure locking after driving-in, which moreover facilitates the insertion of the recessed part through a prior, slightly greater expansion of this opening.
The top and skirt, of plastic, thus have been obtained by molding, the set of molds used having imposed the respective forms described. After formation of the top and the skirt, the skirt is guided with respect to the plate, then drawn by its first end around the latter to the point of immobilization, this being caused by the insertion of the lugs on the plate into the cavities on the skirt. If the driving-in of the skirt around the plate is effected shortly after the formation of the top, the neck is protected immediately after the production of the top of the container. In addition, if, in the area of the first end of the skirt joined to the cover, the neck is provided with a shoulder, it is possible, through observation of the space separating this shoulder on the one hand, and the first end of the skirt on the other, to verify by a rapid visual inspection whether the cover has been torn. As a matter of fact, said space is not the same before and after the tearing of the ring-shaped portion. An inexpensive tamper-proofing indicator is thus obtained.
In another form of the invention, multiple recappings are facilitated and imperviousness is improved by positioning complementary ratchet means at a distance from the nipple or the crown which has only an imperviousness role. These means are located on the outer surface of the neck and on the inner surface of the skirt close to its first end. In this case, the nipple or the crown has a simpler form, cylindrical, without an over-collar and without a recessed shoulder. Its diameter exceeds the diameter of the opening by 3 to 6%.
Whatever the form selected for the nipple or the crown, the first end of the skirt, once the latter is driven-in around the plate to the point of immobilization of the lugs in the cavities, juts out from the apex of the shoulder at a height close to the height of the nipple or crown of the cover. This makes it possible to effectively protect the neck during storage.
In the case of flexible tubes or containers, easy tearing is promoted by a simple rotation around the axis of the opening. Preferably, the form of the specific neck section which defines the form of the inner surface of the first end of the skirt and the form of the periphery of the plate extending from the cover are selected with an axis of symmetry coinciding with the axis of the opening. The distribution of the lugs and cavities follows this axial symmetry.
Thus, if the plate and the specific section of the neck are circular, the inner surface of the skirt is either completely cylindrical with a circular section, or partially cylindrical and partially truncated-cone-shaped. The lugs and cavities preferably are distributed in a regular manner, angularly, for example at 120xc2x0 if they both are three in number. Nonetheless, their number may be more than three, in terms of the general form selected: four for an ellipse, a square or an octagon, five for a pentagon, etc.
The neck unit also may be given a form in accordance with axis symmetry. Thus it may be cylindrical, in the general geometric meaning of the term; that is, with any directional curve whatsoever, the most common sections being, for example, circular, elliptical or polygonal. They also may be completely in the form of a nozzle or connector, connecting the shoulder to the delivery opening, the sections perpendicular to the axis being taken one from the other by homotethy. It even may be cylindrical at its base, near the shoulder, then have a part in the form of a connector near the opening.
One form of the invention is particularly advantageous because it entails a critical reduction in manufacturing cost. In this form the skirt, the inner surface of which is cylindrical, is molded simultaneously with the top, in a temporary position which makes the unit easily moldable, with molds which are easy to produce and an easy unmolding. In this temporary position the skirt thus forms an inverted cap with the plate, the first end of the skirt being connected to the plate by a few bridge extensions of material at the time of molding. The set of molds comprises an upper central mold forming the inner surface of the inverted cap, a set of upper peripheral molds forming the outer surface of the skirt of the inverted cap and the rest of the top, and finally a lower central mold forming the inside of the top.
Preferably unmolding is performed, then the completely cooled molded unit is reworked by drawing it on a core having a form identical to the lower central mold, which is going to serve as a support for the top. A plate comes to rest on the second end of the skirt and effects an axial motion in the direction of the tube, forcing the breaking of the bridges which connected the skirt to the plate, then the driving-in of the skirt around the plate to the point of immobilization of the lugs in the cavities. The complete cooling of the molded unit makes it possible to cut thicker bridges. The latter serving for conveying the material into the skirt during the molding make it possible, if they are thicker, to accelerate production rates and improve the economic conditions of production, although the complete cooling of the molded unit requires an additional device in the production line.
In other forms of the invention, the skirt is produced separately, either isolated or attached to a complete cap. Preferably the cylindrical portion of the inner surface is provided with longitudinal grooves extending from the cavities in the direction of the first end of the skirt. These grooves make it possible to guide the lugs to their trapping in the cavities. They have a depth less than that of the cavities and a width at least equal to that of the lugs. In places these grooves thin out the skirt, which is easily deformable with respect to the lugs. The skirt thus overlaps the lugs without deforming them.
A second purpose of the invention relates to flexible tubes and containers provided with the top manufactured according to the invention. The flexible tube and the container have a plastic top comprising a neck the outlet opening of which is connected by a tearable ring-shaped part to a cover serving as an impervious stopper before the breaking of said ring-shaped part and then being able to be used for recapping of said opening, characterized in that said top is provided with a skirt, said skirt encircling said neck, being provided with means for joining, for example by a ratchet mechanism, with the cover by means of a plate which extends said cover and which is provided with means of joining complementary to those of the skirt; the skirt, cover and plate unit constituting a cap for recapping after tearing of said ring-shaped part.